Why was magnesium sulfate used to dry the organic layer?
From the log of Exp 014:
5.The reaction mixture was rotovaped (set at 100C) again after 45mins on reflux.
6.The resultant compound was washed with water (twice, 70mls and 30 mls) and partitioned in methylene chloride (60mls)
7.After separation; the organic layer was dried over anhydrous Magnesium Sulfate, filtered.
From the log of Exp 014:
5.The reaction mixture was rotovaped (set at 100C) again after 45mins on reflux.
6.The resultant compound was washed with water (twice, 70mls and 30 mls) and partitioned in methylene chloride (60mls)
7.After separation; the organic layer was dried over anhydrous Magnesium Sulfate, filtered.
- Anhydrous magnesium sulfate is commonly used as a desiccant in organic synthesis due to its strong affinity for water
- It forms a hydrate that is insoluble in organic solvents due to its chemical properties and molecular structure.
- Molecules that form hydrates have cavities in their molecular structure which accommodate a certain number of water molecules.
- For example, when magnesium sulfate (MgSO4) is exposed to water it will form hydrates having the general formula MgSO4.nH20.
- Given enough time and enough drying agent, all the water in an organic layer can be incorporated into the inorganic salt.
- When the water is absorbed into the inorganic compound, the salt retains its solid state and can be removed by decanting or gravity filtration.
- The drying agent can be regenerated by heating it to a high temperature.
- Magnesium sulfate is a great drying agent due to its high capacity, completeness in drying, and rapidness.
( Capacity is the amount of water per gram the drying agent holds.Completeness means that drying equilibrium favors the hydrate. )Graphic of Magnesium Sulfate:
( We have learned about solubility properties and likelihood of dissolving in a solvent in Lecture 7 )
Full Marks